ggplot2: Legend overlapping the plot area - is it possible to manually adjust legend position?

Question

Lets say I have a dataset about carrot yield from different fields and different breeds:

carrots<-list(Yield=c(345,226,74,559,288,194),
          Field=c("A","B","C","D","E","F"),
          Breed=rep(c("Long","Short"),each=3))
carrots<-data.frame(carrots)

I want to plot a bar plot showing the yield for each field, coloured by breed:

ggplot(carrots,aes(y=Yield,x=Field,fill=Breed)) +
   geom_bar() +
   opts(legend.direction = "horizontal",
        legend.position = "top") +
   labs(fill="")

But the legend is always slightly overlapping the plot area:

_{(source: users.utu.fi)}

I've tried manually adjusting the legend position to be outside the plot area, such as with

opts(legend.position=c(0.5,1.1)

but then the plot margins cut off the legend and I'm not sure how I can adjust them. Is there a more subtle solution to this problem?

Answer 1

In my environment, the legend does not overlap the plot area at all, but anyway what is overlapping is the background of the legend, so you can remove it by:

ggplot(carrots,aes(y=Yield,x=Field,fill=Breed)) +
 geom_bar() +
 opts(legend.direction = "horizontal",
    legend.position = "top",
        legend.background = theme_blank()) + # this does hack
 labs(fill="")